The present invention is directed to improved Zr-based bulk metallic glasses and more particularly to Zr-based bulk metallic glasses (BMG) prepared with low purity of zirconium under a low vacuum by introducing a small amount of yttrium into the alloy mix.
Recently, many bulk metallic glass forming alloys, such as ZrAlNiCu and ZrTiCuNiBe have been developed. The new types of metallic glasses with excellent glass forming ability (GFA) promise to allow the production of large-scale bulk material by conventional casting processes at a low cooling rate. However, high vacuum (at least 10xe2x88x923 Pa), high purity of constituent elements (the purity of zirconium is at least 99.99 at %, oxygen content should be less than 250 ppm) and high purity of argon gas are necessary for fabrication of the Zr-based bulk metallic glasses (BMGs), even traces of oxygen impurities and other impurities, e.g., carbon, induce the heterogeneous nucleation and reduce the GFA drastically. The strict processing makes the cost of Zr-based BMGs high, and limits its wide application.
Accordingly, an inexpensive reliable method is needed which makes it possible to form Zr-based bulk metallic glasses utilizing low purity Zr and low vacuum.
The present invention is directed to a Zr-based BMG having a small concentration of Y added thereto which can be prepared with a low purity of zirconium under a low. More particularly, the present invention is directed to Zrxe2x80x94Alxe2x80x94Nixe2x80x94Cu and Zrxe2x80x94Tixe2x80x94Nixe2x80x94Cuxe2x80x94Be alloys containing a Y additive.
In one embodiment of the invention 2-4 at % yttrium is added to the Zr-based alloy composition.